Like the 90-pound weakling who suffered as bullies kicked sand on his beach blanket, Jonathan Roosevelt was skinny. Try as he might, the 5-ft., 10-in., 137-lb. Roosevelt just couldn't gain weight. Then, in early 2000, he started training differently, eating more protein and resting more. In a year, he bulked up to 200 lbs., most of it muscle. "Nutrition made a huge difference," he says.

He believes it can make a difference for others as well, including women hoping to lose weight. He's using that conviction to start a new company, adding a crucial dose of passion that was missing from his last venture. Roosevelt is raising $1 million to launch EveryBody, a health club that will combine nutrition counseling with exercise. He has come up with about $200,000 in seed money and is negotiating a lease for the first gym.

Roosevelt, Teddy's great-great-great grandson, says he always found software interesting, but it was never a passion. "I want to get up in the morning and be excited about what I'm doing," he says. For a while he had pursued technology with gusto, first at a venture-capital firm and then at Netscape Communications. There Roosevelt hit on the idea for Epesi Technologies, which tried to simplify the process of integrating new services into large Web sites. After the collapse of the nasdaq, Epesi attempted to shift gears, but couldn't compete with giants such as Microsoft and ibm.

In building EveryBody, Roosevelt is more focused and more deliberate. He interviewed about 25 nutritionists before choosing champion bench-presser Rocco Boulay to join as a vice-president. Boulay's regime stresses metabolism: By building more muscle you burn more calories, even when not at the gym. His proprietary software generates a personalized nutrition-and-fitness plan for each user, complete with meal plans. Specially trained coaches will provide support at no extra charge, and customers will be advised that the program will take a year. Like Roosevelt, they'll need to accept the wisdom of slow but steady.